1. Field of the Invention
The present invention relates to navigation systems, particularly a navigation system which is adaptive to extended navigation facilities, such as the presentation of multimedia information available for moving bodies.
2. Description of the Related Art
Navigation systems have now become a well-known automobile accessories for informing a driver of the current vehicle position and guiding the driver to a specific destination via an appropriate route. For example, a typical navigation system may sense the current position of the vehicle using a current position sensor, retrieve a map in the vicinity of the current position from the map database, and then displays the retrieved map on which the current position is marked. When the user selects a destination, such a navigation system may compute a suitable route to the destination and guide the operator (driver) to the destination, based on the computed route. The set route is typically shown on the display and voice announcements, such as "turn right" or "turn left" are output from a speaker as required.
FIG. 1 shows the basic configuration of an example predecessor navigation system. Navigation hardware 1 (FIG. 1) includes the CPU and other components of a navigation computer, current position sensing and related devices, a map data recording medium, and input/output devices. The applied hardware configuration varies according to the system specification. A device driver 2 (FIG. 1) controls the navigation hardware 1. Navigation programs 4 which implement various kinds of navigation actions are executed under a navigation operating system (OS) 3. The navigation programs include a current position computing program, a route computing program, and a map retrieval program. A navigation system according to this type of configuration is described in, for example, "Development of a New Platform for Car Navigation Systems" (published by Sumitomo Electric Industries, Ltd., No.148, March, 1996, pp. 37-41).
Meanwhile, the development of a more advanced navigation system provided with extended navigating facilities for expanding applications in addition to the above-mentioned basic navigation features is under way. Such system attracts attention as one variant of an Intelligent Transport Systems (ITS). One extended navigating facility is presentation to the user of recommendation information. For example, concerning a public space such as a restaurant is presented as one candidate destination, with multimedia visual and audio information being included in such a presentation. It is desirable that such extended navigating and previously established basic navigating operations be combined and executed in a chain. This kind of navigation system is expected to be compatible with multimedia and networking technologies, providing the user with the versatility of information through the operation in conjunction with telecommunicating infrastructure, such as centers.
In the predecessor navigation system as shown in FIG. 1, however, the navigation programs 4 are platform-dependent, that is, they are specific to a proprietary machine model (the platform refers to the navigation hardware 1 or the combination of the hardware 1 with the navigation OS 3). To implement a chain of basic and extended navigating operations as mentioned above, thus, a discrete extended navigation program which is adaptive to each specific platform model must be prepared. The work load for preparing such a program is high and requires great efforts and time. In situations where customizing on a platform-by-platform basis is required, a car-oriented information system, which distributes such information to many cars from a telecommunicating infrastructure, will become very complex.
As a referential technical approach, ISO-TC204 suggests accessing a map database using Java. However, this suggestion discusses that Java is incorporated into a part of the basic navigating operation, but does not concern the extended operation of navigation.